只是简单的仿某度注册的用户名输入离焦后检验
目录结构
没有涉及到数据库
<!doctype html> <html lang="en"> <head> <meta charset="utf-8"> <title>校验用户名是否存在</title> <script src="js/jquery-3.3.1.min.js"></script> <script> //页面加载完成后 $(function () { //给用户名输入框定义一个离焦事件 $("#username").blur(function () { //获取文本输入框的值 var username=$(this).val(); /* 期望服务器端响应回来的数据格式是这样的(json): {"userexit":true,"msg":"此用户太受欢迎,请换一个"} {"userexit":false,"msg":"用户名可用"} */ $.get("findusernameservlet",{username:username},function (data) { alert(data.msg); var span = $("#s_username") //判断响应回来的数据的键userexit是否为true if (data.usernameexsit){ //true 用户名存在 span.css("color","red"); span.html(data.msg); } else { //false 用户名不存在 span.css("color","green"); span.html(data.msg); } },"json"); }); }); </script> </head> <body> <form action="" method="get"> <input type="text" id="username" name="username" placeholder="请输入用户名"> <span id="s_username"></span><br> <input type="password" name="password" placeholder="请输入密码"><br> <input type="submit" value="注册"> </form> </body> </html>
@webservlet("/findusernameservlet") public class findusernameservlet extends httpservlet { protected void dopost(httpservletrequest request, httpservletresponse response) throws servletexception, ioexception { request.setcharacterencoding("utf-8"); string username = request.getparameter("username"); response.setcontenttype("application/json;charset=utf-8"); map<string,object> map=new hashmap<>(); /*判断浏览器客户端传过来的数据 username true {"userexit":true,"msg":"此用户太受欢迎,请换一个"} false {"userexit":false,"msg":"用户名可用"} */ if ("tom".equals(username)){ map.put("usernameexsit",true); map.put("msg","此用户太受欢迎,请换一个"); }else { map.put("usernameexsit",false); map.put("msg","用户名可用"); } //java:map-->json objectmapper mapper=new objectmapper(); mapper.writevalue(response.getwriter(),map); } protected void doget(httpservletrequest request, httpservletresponse response) throws servletexception, ioexception { this.dopost(request, response); } }
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